JPH0219347A - Production of dimethyl carbonate - Google Patents

Abstract

PURPOSE:To obtain the subject compound useful as a methylation agent, etc., from methanol, carbon monoxide and oxygen in high catalytic activity and efficiency and improved selectivity of carbon monoxide by using a catalyst consisting of a platinum-group compound, a copper salt and a basic complex of magnesium. CONSTITUTION:Dimethyl carbonate is produced by reacting methanol with carbon monoxide and oxygen in the presence of a catalyst consisting of a platinum-group compound (especially preferably palladium), a copper salt (e.g. cuprous chloride) and a basic complex of magnesium (prepared in the form of a methanol solution by calcining magnesium carbonate and reacting the obtained magnesium oxide with methanol and CO2 in an autoclave). The combustion loss of methanol and carbon monoxide can be decreased. Dimethyl carbonate is useful as a production intermediate for polyurethane and polycarbonate and a substitute for extremely poisonous phosgene.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing dimethyl carbonate by reacting methanol with carbon monoxide and oxygen in the presence of a catalyst.

[Prior art and problems to be solved by the invention] Dimethyl carbonate is used as a substitute for highly toxic methylating agents such as methyl iodide and dimethyl sulfate, and in polyurethane, which has become increasingly important as an engineering plastic in recent years. It is an industrially useful substance as a substitute for the extremely toxic phosgene, which is used as an intermediate in the production of polycarbonate and polycarbonate. Methods for producing dimethyl carbonate include: ■Producing by reacting phosgene and methanol;
■Production method by oxidative carbonylation reaction of methanol with carbon monoxide and oxygen in the presence of a palladium-copper redox catalyst (Japanese Patent Publication No. 61-8816.
43338) and (2) a method of producing by transesterification reaction with a carbonate ester. In particular, in method (2), it has been proposed to use an alkali metal halide or a weak alkali metal salt as a cocatalyst.

However, these three manufacturing methods each have the following problems. That is, in method (1) above, the toxicity of phosgene is extremely strong and the electrolytic chlorine required to produce phosgene is expensive, and in method (2) above, methanol is used.

- The combustion loss of carbon oxide is large; - The selectivity of carbon oxide is low; and the reaction rate is low; and the method (2) above requires a multi-step reaction process.

Based on such prior art, the present invention is based on methanol, -
In the method for producing dimethyl carbonate from carbon oxide and oxygen, further reducing the combustion loss of methanol and carbon oxide,
It is an object of the present invention to provide a method for obtaining dimethyl carbonate in high selectivity and in increased amounts.

[Means to solve the problem]

The present inventors have made extensive efforts to develop a cocatalyst for the reaction of producing dimethyl carbonate from methanol, carbon oxide, and oxygen using a palladium-copper redox catalyst system. Basic magnesium complex, which is a base developed (Japanese Patent Publication No. 56-54298
) is excellent as a cocatalyst in increasing the production rate of dimethyl carbonate and reducing the combustion loss of carbon oxide, and has been found to be able to sufficiently overcome the above-mentioned drawbacks, and the present invention provides It has arrived.

That is, the present invention provides a method for producing dimethyl carbonate, which is characterized by reacting methanol with carbon monoxide and oxygen in the presence of a catalyst consisting of (1) a white metal compound, (2) a copper salt, and (3) a basic complex of magnesium. This is what we provide.

In the present invention, -carbon oxide partial pressure is usually 0.5 to 2Q
methanol is reacted with white metal compounds, copper salts and Dimethyl carbonate is produced by reaction with oxygen and carbon monoxide in the presence of a catalyst consisting of a basic complex of magnesium.

As the platinum metal compound, compounds such as ruthenium, rhodium, and palladium are used, and palladium is particularly preferred.

The platinum metal compound is used either as an elemental metal or as a metal salt such as a halide, nitrate, sulfate, phosphate, acetate, or sulfonate.

In addition, these can be activated carbon, graphite, alumina, silica, silica-alumina, diatomaceous earth, polyvinylpyridine,
Those supported on carriers such as magnesia and calcia are also used.

Copper salts include halides such as cuprous chloride and cupric chloride, as well as copper oxychloride, nitrates, sulfates, sulfonates, acetates, benzoates, oxalates, and phosphates. be done.

The basic complex of magnesium is disclosed in Japanese Patent Publication No. 56-54298.
According to the described production method, a methanol solution prepared by reacting magnesium oxide obtained by calcining magnesium carbonate, methanol, and carbon dioxide in an autoclave is used.

In addition, the catalyst of the present invention contains, in order to improve the solubility of copper salt,
Magnesium halides such as chlorides, bromides, and iodides can also be used in combination.

In carrying out the present invention, an excess amount of methanol as a raw material or dimethyl carbonate produced by the reaction is usually used as a solvent, but it is also possible to use a separate solvent.

Examples of solvents include hydrocarbons such as benzene, toluene, xylene, octane, and decane, ethers such as dibutylethenopeteterahydrofuran and ethylene glycol dimethyl ether, and ethyl acetate, methyl benzoate, and ethyl acetonitrinobenzonitrile such as ethylene carbonate. Nitrile, amides such as N-methylpyrrolidone, N,N-dimethylacetamide, and ureas such as ethylenedimethylurea are used.

The method of the present invention is carried out either batchwise or continuously in a liquid phase under the following conditions. The temperature conditions are 50 to 200℃, -
It is used at a carbon oxide partial pressure of 0.5 to 20 kg/cm" and an oxygen partial pressure of 0.05 to 1Q kg/cm2. The amount of the platinum metal compound used is usually 0.0001 per 1 β of the reaction solution.
~10g is used. The amount of copper salt used is 0.5 to 100 times the weight of the white metal compound.

The basic complex of magnesium is prepared according to Japanese Patent Publication No. 56-54298, and the amount used is 0.5 to 100,000 times the weight of the white metal compound in terms of magnesium oxide. When magnesium halide is used in combination, the amount used is preferably 0.5 to 20,000 times the weight of the white metal compound.

〔Effect of the invention〕

By the method of the present invention, the selectivity of -carbon oxide is improved, and dimethyl carbonate can be obtained efficiently with high activity.

〔Example〕

Next, the details of the invention will be explained with reference to some examples illustrated below, but these examples are not intended to limit the invention.

Reference example (preparation example of basic complex of magnesium) 23, 2
When 7 g of magnesium carbonate was calcined in an electric furnace at 500° C. for 7 hours, 10.20 g of “active” magnesium oxide was obtained.

5.0 g of "active" magnesium oxide and 165 methanol were placed in a 500 rnl autoclave equipped with a stirrer, and the inside of the autoclave was purged with nitrogen. Next, 14゜Qkg/cm" of carbon dioxide was injected under pressure, and the reaction was allowed to proceed at room temperature for 4 hours. The gas absorption was 3.5 kg/cm2, and the resulting liquid was homogeneous. This liquid was mixed with basic magnesium Methanol solution of complex (magnesium standard 0.7
52 mol/β) was used in the following examples.

Example 1 Palladium chloride 0.30 mmol and cuprous chloride 7.5 were placed in a 380 d autoclave with a Teflon-treated stirrer.
3.75 mmol of magnesium chloride, 10 ml of a methanol solution of a basic magnesium complex, and 30 mmol of methanol were added, and the inside of the autoclave was purged with nitrogen. Next, 10.3 kg/cm' of nitrogen, 2.7 kg/cm2 of carbon oxide, and 7.3 kg/7 cm2 of argon gas containing 19 mo1% oxygen were injected, and the autoclave was kept at 130°C and reacted for 1 hour. After cooling to room temperature and releasing the pressure, the reaction gas and reaction product liquid were analyzed by gas chromatography to quantify the amount of dimethyl carbonate produced and the amount of carbon monoxide reacted. As a result, 12.3 mmol of dimethyl carbonate was obtained, S Co-[I
MC (note) was 41%.

(Note) Selectivity of carbon monoxide to dimethyl carbonate (S CO-
DMC) is represented by the following formula.

Example 2 Palladium chloride A 0.30 mmol, cupric chloride 7.5 m
mol, methanol solution of basic magnesium complex 10
1nI! Example 1 using 30 ml of methanol and
performed the same operation. As a result, dimethyl carbonate is 21.6
mmol was obtained, and S Co-DMC was 76%.

Comparative Example 1 Palladium chloride 0.30 mmol, cuprous chloride 7.5 m
mol.

Potassium chloride A 15. The same operation as in Example 1 was carried out using 15.0 mmol of Qmmo 1 , potassium methylate) and 40 ml of methanol. As a result, 4.2 mmol of dimethyl carbonate was obtained, and 24 mmol of S CO-DMC was obtained.
%Met.

Claims (1)

[Claims] A method for producing dimethyl carbonate, which comprises reacting methanol with carbon monoxide and oxygen in the presence of a catalyst consisting of (1) a platinum metal compound, (2) a copper salt, and (3) a basic complex of magnesium.